High frequency signaling



1932- H. CHlRElX 1,892,383

' HIGH FREQUENCY SIGNALING Filed April 29, 1931 2 Sheets-Sheet 1 v yenlbr l e 21rd C/Lredx oer W Hazy-m DEC. 27, c E X HIGH FREQUENCYSIGNALING Filed April 29', 1931 '2 Sheets-Sheet 2 Patented Dec. 27, 1932UNITED STATES PATENT OFFICE HENRI CHIREIX, F PARIS, FRANCE, ASSIGNOR TOSOCIETE FRANCAISE RADIO- ELECTRIQUE, OF PARIS, FRANCE, A CORPORATION OFFRANCE HIGH FREQUENCY SIGNALING Application filed April 29, 1931, SerialNo. 533,674, and in France May 6, 1930.

are useful to satisfy particular requirements which are of greatimportance for application in radio broadcasting.

The novel features and objects of the invention will be more clearlyunderstood by 5 reference to the following description taken togetherwith the accompanying drawings which diagrammatically represent a highfrequency signaling station.

The figure has been divided into two halves,

the left half being termed Fig. 1 and the right half Fig. 1a, and thesehalves are subdivided upon each of the two drawings into separatesections by dotted lines, each section diagrammatically including agroup assembly of the apparatus to which a definite function can beascribed. Thus, section 1 contains the carrier wave generator, section 2the source producing the modulated current, section 3 the couplingdevice with amplifier, section 4 the modulator, sections 5 and 5b thelow energy amplifiers, sections 6 and'6b the intermediate energyamplifiers, and sections 7 and 7 b the high energy amplifiers.

r Heretofore, it has been known to transmit a modulated wave inaccordance with the following method.

By means of a generator, carrier waves are produced consisting of afirst unmodulated wave and a second wave of the same frequency and inphase quadrature with the first mentioned wave. By modulating theamplitude of this second wave, a resultant wave can be obtained having asingle modulated phase of an amplitude which remains practically aconstant. In an arrangement for producing two resultant waves of thissort, shiftable in phase over a certain angle, whereby the variations inphases due to the modulation is af- K fected symmetrically with respectto the bisection of this angle, it is possible by superposing thesewaves in opposition to obtain a wave with modulated amplitude which canbe transmitted over the antenna. Before the superposition takes place,each phase modulated wave can of course be amplified by an lndependentamplifier having a number of desired stages. i

Referring now to section 1-, a master oscillator 11 is provided, beingstabilized by a quartz crystal 12, the currents being generated in theoscillating circuit L C In section 3 an equilibrated Wheatstone bridgeis provided including four self inductances L L etc. A condenser C inserles wlth an ammeter 33 constitutes one diagonal ofthe bridge. Anotherdiagonal includes the condenser C the ammeter 32,

and the coupling condenser G Two of the self inductances L are shuntedby fixed resistances P while the other two self inductances are shuntedby the internal resistances of two tubes 31, arranged in push-pull.These two tubes serve to affect one diagonal of the bridge by means ofpure carrier waves from the master oscillator 11 through the in-"termediate action of the'variable L 0. coupling The other diagonal ofthe WVheatstone bridge is influenced indirectly by the same masteroscillator 11 through the intermediate action of the variable coupling Lof the tube 21 provided in section 2 and the circuit of L C which areconnected to the terminals of condenser G The plate current of tube 21is modulated according to above method'by controlling the anode by meansof the modulator of section 4, which includes comprising an entrancetransformer 40, a cascade of amplifiers 41, 42, 43 (the last stage beingone of high energy), and a branch containing an iron self inductance 44provided between the plates of the last stage and one terminal of thecondenser G The output voltages of the Wheatstone bridge are transmittedby the intermediate coil L to the input of the amplifiers 51 of sections5 and 5b, and the currents therefrom are amplified respectively by thetubes 61 of sections 6 and 6?), each tube 61 preferably representing twotubes connected in parallel, and finally in the stages of the stages 7and 7 b, the amplification takes place in the tubes 71, each tubedesignating in rheumatic man ner six tubes connected in parallel. Theoutput terminals of the stages 7 and 7 b are symmetrically connected andthe antenna 8 is connected to the center point of the common circuitthus formed.

The stages 5- -6, 67 of amplification 5b6b, 66-775 are capacity coupled.Each coupling circuit includes two circuits, a pri-.

mary circuit and a secondary circuit. Be tween stages 5 and 6, theprimary and secondary circuits each includes self inductances and equalcapacities L and C between the stages 6 and 7 the primary circuitincludes the self inductance L and the capacity G while the secondarycircuit includes the self inductance L and the capacity v The couplingis obtained by means of condensers G and G respectively. Each primarycircuit is damped by the internal resistance of the preceding tube, andthe secondary circuits by the resistance P and P respectively.

In designating the coeillcient of coupling of the two circuits by K, (Kbeing such that the waves of the coupling ofthe undamped circuit berespectively XoJl-K and ho /l +K),

designating the excess voltage by S (which may be represented Thecalculation shows that this arrangement in fact assures a definitefilter-band. This at once implies an output of which is practicallyinadmissible for he last stage.

The output circuits in sections 7 and 7b each includes a self inductanceL and condenser C and a coupling capacity G These capacities Gr areconnected for the purpose of forming common circuit.

The coupling circuits are coupled in like manner as the self inductancesof the Wheatstone bridge with coils L and in series with the capacitiesN which are connected to the grids of the preceding tubes for thepurpose of com ensatin their capacities ro er. h p

In order to provide for correction of the individual polarization of thetubes of greater power of the stages 6 and 7, the grids are inductivelyenergized from separate coils.

Likewise the self inductance L is coupled with six hand madesecondarycoils 6 and each connected to a grid of the tubes of the last stage -7.Also the inductance L is coupled with two secondary coils in order toobtain correspondence with the two tubes of the stage 6. I H g I Thecircuit L C R of modulator section 4: for the amplifier of musical.frequency in a col-rector circuit, designed to compensate for theirregularities of the filter curves of the circuits of sections 3, 55?),66b, and 7-77).

The apparatus operates in the following manner: 7

The lVheatstone bridge of I'section 3 is tuned to the supporting wave bymeans of condensers G and C whereby it will be noted at once that thedirect coupling L0 be tween the generator of the carrier wave and thebridge results in producing voltages in the inductances L in oppositephase, of a fixed amount and unaffected by the modulation.

On the other hand, the bridge tuned by the capacity C behaves like asecondary circuit capacitatively'coupled with the terminals of thecondenser G to a primary circuit L C Under these conditions the currentsof the secondary circuit are always in quadrature with those of theprimary circuit.

The'circuit L C when thus subjected to a voltage having a modulatedamplitude and in phase with that of the generator 1, makes it evidentthat the indirect coupling L0 will induce a modulated current in thebridge which is in quadrature with that of the primary circuit, i. e. inquadrature also with the current due to coupling L0 The voltages in Lare therefore in phase due to coupling L0 and subject to the modulationand individually in quadrature with the preceding voltages.

It is evident that in this arrangement, the amplifiers of sections 5 and5b are each energized by two voltages obtained from couplings L0 and L0respectively.

By selecting these couplings in such a manner as to render the modulatedvoltage relatively small as compared with the unmoclulated voltage, theresultant energizing voltages of the tubes of the sections 5 and 56 Willbe practically of constant and absolute value but will presentthemselves a variable shifted phase between themselves.

These voltages amplified on the one hand, by the amplifiers 6 and 7 and6b and 76, on the other hand, will produce currents of practicallyconstant intensity but of variable phase in the circuits L C Theconstruction of the couplings will be selected in such manner that theunmodulated current from coupling L0 produces opposed memes voltagesupon the plates of the tubes of the last stage, and underthesecircumstances, none of the voltages will be concentrated at theterminals of the capacities G and therefore no current will have anyeffect on the antenna.

In fact, the modulated wave will appear in the antenna in the sameorder'as in the circuit L12, 012, of the section 2.

In arranging the Wheatstone bridge according to the invention, a filterband is obtained. On the other hand, due to the fact that the inductiontakes place in two diagonals or branches, no reaction of one elementagainst the other can occur.

The advantage of the above described arrangement resides in the factthat the tubes of the stages 5, 6, 7 5b, 6b, and 7b operate with anoscillation whose amplitude is practically constant. The outputattainable is of a greatly increased value which could not possibly beobtained in the absence of an unmodulated wave owing to the presence ofcoupling L0 What I claim is:

1. Transmitter of modulated high frequency currents comprisingaiVheatstone bridge consisting of four impedances and having tuningmeans inserted in the diagonals thereof, means for applying to one ofthese diagonals a carrier wave, means for applying to the other diagonalanother continuous wave of the same frequency but in quadrature with theforegoing carrier wave, amplitude modulation means for this lattercontinuous wave, two symmetrical circuits coupled to the VVheatstonebridge each circuit comprising amplifiers in cascade, a common circuitassociated with the output from the amplifiers and an antenna coupled tothe said common circuit.

2. Transmitter of modulated high frequency currents comprising aWVheatstone bridge consisting of four impedances and having tuning meansinserted in the diagonals thereof, means for applying to one of thesediagonals a carrier wave by the intermediary of a symmetrical valvearrangement, means for applying to the other diagonal another continuouswave of the same frequency but in quadrature with the foregoing carrierwave, amplitude modulation means for this latter continuous wave twosymmetrical circuits coupled with the Wheatstone bridge each circuitcomprising amplifiers in cascade. a common circuit associated with theoutput from amplifiers and an antenna coupled to the said commoncircuit.

3. Transmitter of modulated high frequency currents comprising aVVheatstone bridge consisting of four impedances and having tuning meansinserted. in the diagonals thereof. means for applying to one of thesediagonals a carrier wave. means coupled 011 the one hand with the sourceof the said carrier wave and on the other hand associated with a circuitconnected the terminals of a condenser inserted in the other diagonal inorder to apply to this latter a continuous wave in quadrature with theforegoing carrfer wave,':amplitude modulation means for this lattercontinuous wave, two symmetrical circuits coupled to the l/Vheatstonebridge each circuit comprising amplifiers in cascade, a common circuitassociated with the output of the amplifiers and an antenna coupled tothe said common circuit.

l. Transmitter of modulated high frequency currents comprising aWheatstone bridge having tuning means inserted in the diagonals thereof,means for applying to one of these diagonals a carrier wave, means forapplying to the other diagonal another continuous wave of the samefrequency but in quadrature with the foregoing carrier wave, amplitudemodulation means for this latter continuous wave, two symmetricalcircuits coupled to the Vheatstone bridge each circuit comprisingamplifiers in cascade, the stages of which are capacitatively coupled, aresistance shunting the secondary coupling circuit in each stage, acommon circuit associated with the output of the amplifiers and anantenna coupled to the said common circuit.

5. Transmitter of modulated high frequency currents comprising aWheatstone bridge consisting of four impedances and having tuning meansinserted in the diagonals thereof, means for applying to one of thesediagonals a carrier wave, means for applying to the other diagonalanother continuous wave of the same frequencybut in quadrature with theforegoing carrier wave, amplitude modulation means for this lattercontinuous wave, two symmetrical circuits coupled to the Wheatstonebridge each circuit comprising amplifiers in cascade, the stages ofwhich are capacitatively coupled, a resistance shunting the secondarycoupling circuit in each stage, an inductance and a capacity insertedbetween the input of the valve feeding each coupling and a point of thiscircuit, a common circuit associated with the output of the amplifiersand an antenna coupled to the said common circuit.

6. Transmitter of modulated high frequency currents comprising aVVheatstone bridge consisting of four impedances and hav'ng tuning meansinserted in the diagonals thereof, means for applying to one of thesediagonals a carrier wave, means for applying to the other diagonalanother continuous wave of the same frequency but in quadrature with theforegoing carrier wave. amplitude modulation means for this latter contnuous wave. two symmetrical circuits coupled to the Wheatstone bridgeeach circuit comprising amplifiers in cascade each consisting of fourimpedances and stage of which comprises a certain number of valves, theinput of each of these valves being connected to biasing means throughindividual self-inductances coupled to a common coupling circuit acommon circuit associated with the output of the amplifiers and anantenna coupled to the said common circuit.

HENRI CHIREIX.

